{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,18]],"date-time":"2025-12-18T06:47:00Z","timestamp":1766040420165,"version":"3.48.0"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,12,18]],"date-time":"2025-12-18T00:00:00Z","timestamp":1766016000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Public Health"],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Cytokeratin 19 fragment (CYFRA 21-1) is an important biomarker of lung cancer. There are clinical observations of elevated serum levels of lung cancer biomarkers in patients with viral pneumonia. However, the clinical significance of CYFRA 21-1 in coronavirus disease 2019 pneumonia has not been investigated.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      This retrospective study included 252 patients with community-acquired pneumonia (CAP) between December 1, 2022, and September 30, 2023. They were classified into three groups by clinical diagnosis and severity, namely mild non-COVID-19 CAP (\n                      <jats:italic>n<\/jats:italic>\n                      \u202f=\u202f86), mild COVID-19 (\n                      <jats:italic>n<\/jats:italic>\n                      \u202f=\u202f100), and severe COVID-19 (\n                      <jats:italic>n<\/jats:italic>\n                      \u202f=\u202f66). Demographic characteristics, history, outcomes, and laboratory tests, including CYFRA 21-1 levels, were collected and compared among the groups. Risk factors associated with the diagnosis of COVID-19 pneumonia and severity were explored using appropriate statistical methods.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      CYFRA 21-1 levels progressively increased from mild non\u2013COVID-19 CAP to mild COVID-19 and severe COVID-19. Lower lymphocyte and platelet counts, alongside elevated CYFRA 21-1 levels, were associated with COVID-19 pneumonia. Multivariate analysis identified CYFRA 21-1 as an independent diagnostic [diagnosis odds ratio (OR)\u202f=\u202f2.369; 95% confidence interval (CI)\u202f=\u202f1.638\u20133.605;\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.001] and prognosis factor of COVID-19 pneumonia (severity OR\u202f=\u202f1.416; 95% CI\u202f=\u202f1.119\u20131.867;\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.01). The area under the receiver operating characteristic curve of CYFRA 21-1 for predicting the development of severe COVID-19 pneumonia was 0.913. Spearman analysis showed a negative correlation between CYFRA 21-1 levels and oxygenation index, with a correlation coefficient of \u22120.278 (\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.024).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>CYFRA 21-1 may be a potential diagnostic and prognostic indicator of COVID-19 pneumonia. Prospective multicenter studies are needed to confirm its clinical value.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fpubh.2025.1738947","type":"journal-article","created":{"date-parts":[[2025,12,18]],"date-time":"2025-12-18T06:44:29Z","timestamp":1766040269000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Clinical significance of cytokeratin 19 fragment in COVID-19 patients: a retrospective 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